340 water neck leak.

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ltrripp11

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gentleman

ive had enough chasing a small water leak at the thermostat neck on my 340. the surfaces have been cleaned and scothbrited lightly down to bare metal and new gaskets and light rtv sealant used twice but still seeps lightly. the intake manifold is new performer rpm but the neck is the original. im thinking on replacing the neck. i heard the chrome ones dont seal well but is this just a myth? anyone have chrome that is not a problem? dont want to waste the money and still have no seal. ive also seen the chrome with o-ring type on e-bay. are these any good? just trying to do my homework before i buy. thanks.
 
I had that problem, and it about wore me out. Must have taken apart and put new gasket and sealant on it a half dozen times.

Turned out that the aluminum intake (LD340) had the bolt holes for the thermostat housing, all the way through to water. The water was leaking back up around the threads.

I put studs in it, with thread sealant (silicone will work also) then the problem was solved. Mine is dryer than a bone now.

I agree, with the chrome water outlets, you couldn't give me one.
 
You may will find that the gasket surface is warped, drag a file across it
and that will tell you right away. Keep filling until the pattern is the same across the surface, remember to keep the fill flat at all times.
 
Save your money, the chrome ones are crap..been there done that...I had one years ago crack at the neck and the coolant leaked down under the hose and it looked like it was leaking from the joint.
I have put my housing on a belt sander to get it level worked great.
AL
 
RTV is required any bolt screwed into water including most thermostat housing bolts.
Years ago a friend of mine had a aftermarket aluminum intake on a big block chevy. That intake had a serious step in the mating flange. Took over an hour to carve that one down to flat.
 
chrome also does the weird electrolys (sp) thing. No chrome around water or electricity.
 
Chrome sucks.

Got a billett one from mancini's.

Had to take a wet stone to the mating surface on the intake to remove all the pits.

Used a gasket and red permatex to finally get mine to quit leaking/seeping, but I think the biggest help was getting the pits out of the intake with the wet stone.
 
Mines been leaking to and its getting on my nerves. Tomorrow I am getting a wet stone and going to town.
 
67ragtop said:
Mines been leaking to and its getting on my nerves. Tomorrow I am getting a wet stone and going to town.
Click to expand...

a file or medium grit sandpaper on a flat block will work. The goal is flat plane on mating surfaces and a finish that provides a tooth for the sealant. Chrome doesn't provide either of .
 
thanks fellas. no chrome it is. well i guess im not the only one aggravated...
 
I made a gasket out of an old radiator hose. It's rubber and seals perfectly even with a chrome thermostat housing. Plus it's reusable and free, no sealant or scraping required.
 
I've had a chrome one on for 12 years -

you take a file to the mating surface, clean it all off

you take rtv and use it on both sides of the gasket

you seal the intake bolt threads

you let it setup dry overnight and fill it up the next day

I;ve used this method for years now with no issues.
 
Believe it or not but I used a Billet Specialties 360° Swivel Billet Water Neck for a Chevrolet. No more paper gaskets, no more leaks and no more problems. I mated it to fit on the M1 manifold with very little work and I will do again in a heartbeat
 
I run a 6 PK and also had to use the Ugh chev swivel neck. cleaned my intake good with a file to make sure it was flat . been on there i guess for 4 years no leak.
 
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